Conventionally, the mainstream of semiconductor device production is the mass production of single-type products (single-type lots), such as DRAMs. Hence, a projection exposure apparatus frequently processes single-type lots repeatedly and keeps a continuous operation over a long period of time.
In recent years, however, many different types of specially ordered LSI products, such as ASICs, are produced in small lots more and more frequently, and the lot to be manufactured by one projection exposure apparatus is often changed in a short period of time. In this situation, an operation control scheme to process consecutive lots efficiently is required. As an example of such an operation control scheme, a batch process technique is known with which control information on a lot to be produced is reserved, and when the manufacture of a lot, which is presently being processed, is complete, the process of the next lot is started automatically based on the reserved control information.
According to the method disclosed in Japanese Patent Laid-Open No. 2001-307972, by the present applicant, before the process of a lot, which is presently being processed is complete, a substrate for the manufacture of the next lot is transported in advance to a wafer preparation completion position in accordance with the presence/absence of the recipe (control information) of the next lot. The ON/OFF state of the power supply of an exposure apparatus necessary for the lot process is controlled to suppress a time loss that occurs when lots are to be changed over.
In Japanese Patent Laid-Open No. 2001-307972, after the substrate of the next lot is transported to the wafer preparation completion position, correcting processes for various types of devices are performed. More specifically, in order to maintain a high accuracy for focusing of aligning the substrate (wafer) surface with the image-forming surface (focal plane) of a reduction projection lens and a high alignment accuracy for alignment of overlaying a pattern to be projected with a to-be-projected region, when products (lots) are to be changed over, an adjustable correction parameter is automatically measured in advance before exposure of the substrate, and the parameters of organized constituent components (units) are set at appropriate values. This prolongs a time before exposure.
In particular, to cope with recent small-feature devices, these correction parameters must be measured more accurately. Accordingly, the measurement time of the correction parameters further increases and the number of types of the correction parameters tends to increase more and more. Consequently, when the many-type, small-lot manufacture as described increases, the time required for correction parameter measurement in changing over the products (lots) increases. An efficient process is required in this respect as well.
Preprocesses of the respective units, e.g., alignment of an original (reticle) having a pattern, gas exchange of a pulse laser source, calibration of the laser beam wavelength, adjustment of the light quantity of the measurement light of a wafer alignment scope, setting of illumination conditions that optimize resolution of a mask pattern, and the like, are performed each time the lots are to be changed over. A time loss due to these processes increases as the product (lot) changeover frequency increases.